Coaxial suction and delivery valve arrangement for high pressure compressors and pumps



March 14, 1967 H. BAUER ETAL 3,309,014

COAXIAL SUCTION AND DELIVERY VALVE ARRANGEMENT FOR HIGH PRESSURECOMPRESSORS AND PUMPS Filed Aug. 10, 1965 ATTORNEYS United States Patent3,309,014 COAXIAL SUCTION AND DELIVERY VALVE AR- RANGEMENT FOR HIGHPRESSURE COMPRES- SORS AND PUMPS Helmut Bauer, Basel, Anton LeitgebAesch, near Basel, and Albert Strebel, Binningen, near Basel,Switzerland, assignors to Maschinenfabrik Burckhardt A.G., Basel,Switzerland, a corporation of Switzerland Filed Aug. 10, 1965, Ser. No.478,716 Claims priority, application Switzerland, Aug. 11, 1964, 10,496/64 Claims. (Cl. 230231) The present invention has for its objectimprovements in arrangements including coaxial suction and deliveryvalves for high pressure compressors and pumps.

Such high pressure valve arrangements are known wherein a central bodycarrying the valve is provided with an axial channel or bore cooperatingwith the delivery valve and, round said axial channel or bore, withsloping channels leading to the suction valve. Said sloping channelsconnect an annular chamber inside which the suction pressure prevailsand which surrounds the central body with the seat of the suction valve.

In valves of such a type intended for pumps and compressors operatingunder service pressures which may reach several thousand atmospheres,the material forming the different parts of the valve elements issubjected to stresses which are much higher than the stresses which aregenerally allowed in the execution of machines under conventionalpressures. The constant modifications in the value of the pressureduring the suction and compression strokes produce, in particular inregistry with the sharp ridges and acute angles in the fluid conveyingchannels in the valve arrangement, load peaks which may lead readilythrough excess straining to breakage. It is possible to reduce suchstresses by suitably rounded connecting surfaces and by machining thesharp ridges, but it is impossible thus to cut out completely thestresses.

In cylinders and containers subjected to a high constant inner pressure,these load peaks and stresses have generally no detrimental action,since upon a local rise above the stress limit of the material at thepossible points of shearing, the stress peak for the material consideredis compensated by a suflicient elongation obtained through extrusion andplastic deformation; with a localization of the extrusion area, there isno risk of breaking after a certain time. In coaxial suction anddelivery valve arrangements fitted in high pressure compressors andpumps, in contradistinction, the pressure varies at each cycle betweensuction pressure and compression pressure and this has an action chieflyon the central valve-carrying body inside which the delivery and suctionchannels are formed, said modifications in pressure acting moreparticularly in the area extending between the surface fluidtightlyclosing the suction valve and the surface fluidtightly closing thedelivery valve. During said modifications in pressure, the maximumstress involved is unimportant whereas, what is important as far as therisk of breakage is concerned is the difference between the maxi mum andminimum stresses.

The present invention has for its object a coaxial suction and deliveryvalve arrangement operating under high pressures, wherein thedetrimental action of the variations in stresses and consequently theshearing efforts, in particular as concerns the channels formed in thecentral body of the valve-carrying arrangement, are considerably reducedwhile the risk of breaking after a certain time is cut out to a largeextent.

To this end the outer periphery of the central body extending betweenthe packing which is to make the central body fiuidtight with referenceto the valve casing and the seat of the suction valve and including thesloping channels, is subjected to a constant suction pressure over alength substantially equal to the length of the central passage orchannel subjected to the varying pressure prevailing in the cylinder.Thus, the stresses produced :by the variations in pressure are reducedas far as the central body is concerned.

Furthermore, in order that the variable stresses which may still appearin the area corresponding to the sloping passages surrounding thecentral channel, may not act detrimentally by a shearing action or by anincrease in the stresses, the present invention also provides, accordingto a further advantageous feature, a reduction in the shearing action bygiving the surface ensuring fluidtightness with the annular suctionvalve a part-spherical shape, whereas the bearing surface forming anextension of said spherical surface of the central body is urged underpressure against a ring constituted by a material having a high modulusof elasticity. Thus, as a consequence of the friction along the bearingsurface associated with the fiuidtight surfaces forming the output areafor the sloping channels, the modifications in shape in the central bodyare reduced to a large extent.

Further features and advantages of the invention will appear in thereading of the following description, reference being made to theaccompanying drawing, the single figure of which is an axial sectionalview of a preferred embodiment of a coaxial valve arrangement accordingto the invention.

The arrangement illustrated forms an assembly of coaxial suction anddelivery valves for high pressure compressors and pumps. The fluidpasses during the suction stroke of the piston into the cylinder bore 4through the sloping channels 2 arranged in the central body 1, saidchannels2 being distributed round the axial channel 3. During thecompression stroke, the fluid passes through the axial channel 3 in thecentral body.

During the suction stroke of the pump or compressor operating under highpressure, the fluid, passing out of an annular chamber 5 formed in thevalve casing subjected to the suction pressure and surrounding thecentral body 1, enters the sloping passages or channels 2 so as to reachthe seat 7 of the member 8 forming the suction valve, following whichthe fluid passes over the latter and the stop 9 projecting into the bore4 of the cylinder so as to reach finally the said bore 4.

During the compression stroke, the fluid to be compressed passes throughthe channel 3 into the central body 1, passes over the plate-shapedmember 10 forming the delivery valve and reaches the annular chamber 11beyond said valve, said annular chamber 11 being subjected to thecompressor pressure.

By reason of the pressure prevailing in the annular chamber 11 andacting on the front surface 12 of the coaxial suction and deliveryarrangement projecting into the annular chamber 11, the central body 1is urged towards the front surface 6 of the inner ring 14 fitted insidethe intermediate ring 13. The front surface 6 and the cooperatingsurface of the body 1 engaging said surface 6 are machined in a mannersuch that the pressure acting in said central body allows obtainingfluidtightness.

In order to ensure a perfectly reliable engagement on the bearingsurface 6, for instance at the moment of the starting of the compressorbefore any compression is obtained, there is inserted between the frontsurface 12 of the valve arrangement and the cover 15 forming thecylinder head, an elastic member 16 as known per se. The fluidtightnessbetween the chamber 11 inside which a constant pressure prevails and thesuction chamber 5 formed inside the cylinder head and also subjected toa constant pressure, is obtained by means of an annular packing 17 andconsequently the portion of the cylinder bore 18 in the cylinder headextending between the annular suction chamber 5 and the annularcompressionv chamber 11 forms a guide for the central body 1.

According to the invention, the area of the central body 1, registeringwith the central channel 3 subjected to the variable pressure prevailinginside the cylinder and extending between the incurved surface 7 closingthe annular body 8 forming the suction valve and the fluidtight surfaceon the member 10 forming the delivery valve, is sujected together withthe oblique channels to a constant suction pressure over a length whichis substantially equal to its outer'periphery between the packing 17 andthe bearing surface 6. Thus, by reason of the suction pressure exertedon said peripheral area of the central body 1, the stresses to which thelatter is subjected under the action of the varying pressure arereduced.

In order that the varying stresses still extend in the area registeringwith the channels 2 surrounding the 'central bore 3 may not lead to adetrimental shearing effect or to an increase in the tensioningstresses, such increases in stresses arising in the area correspondingto the sloping channels 12 and which are transmitted with an increasedvalue towards the surface 7 fiuidtightly engaging the suction valve 8are considerably reduced in accordance with the invention by reason ofthe central body 1 being subjected to a suction pressure throughout thearea extending between the packing 17 and the bearing surface :6engaging the ring 14 fitted in the intermediate ring 13, andisfurthermore subjected in registry with said surface 6 engaging the ringto a large superficial pressure, while said ring :14 is constituted by amaterial having a modulus of elasticity which is much higher than thatof the material forming the central body 1.

The deformations of the ring 14 are reduced by reason of its highmodulus of elasticity and the friction exerted on the bearing surface 6also reduces the deformation of the adjacent area of the body 1.Similarly, the strain to which the central body 1 is subjected and whichis proportional to the modifications in shape are reduced in conformitywith Hookes law. The fluidtig-ht seat surface 7 and the correspondingsurface on the annular body 8 forming the suction valveare curvilinear.The axes of the sloping channels vcoincide preferably with radii of saidincurved surfaces so as to reduce the risk of shearing.

The pressure exerted on the bearing surface 6 and the higher modulus ofelasticity of the ring 14 with reference to the modulus of the materialforming the central body are such that the peaks of the stresses arisingin registry with the incurved fluidtight surface 7 and ascribable to ashearing action, are reduced in a manner suflicient to cut out inpractice any risk of a break.

Numerous modifications and additions may be brought to the system ofcoaxial valves described hereinabove,

a flat outer extension for said part spherical section, an annularsuction valve having a surface matching said part spherical surface andcooperating with the openings of the sloping channels facing thecylinder, a delivery valve cooperating with the opening of the axialchannel in the body at the end thereof facing away from the cylinder,and means-whereby the portion of the outer periphery of the bodyextending between said openings of the sloping channels and said openingof the axial channel is subjected to suction pressure over a lengthequal to that of the axial channel subjected to the pressure in themachine cylinders 2. A coaxial suction and delivery valve arrangementadapted to equip high pressure compressors and pumps valve and thesurface fluidtightly engaging the delivery valve, is equal to the lengthof the axial channel subjected to the pressure prevailing inside thecylinder.

3. An arrangement as claimed in claim 2, wherein the risk of shearing isreduced by reason of the surface forming a seat for the suction valvebeing constituted by a fraction of a sphere surf-ace, and the surface ofthe .central body extending beyond said part spherical seat surface isurged under pressure against the end surface of a cylindrical ringinside the cylinder constituted by a material having a high modulus ofelasticity whereby the deformations of the central body are considerablyreduced by the friction to which said ring end surface is subjected andby the shape given to said seat of the suction valve as a fraction of ,asphere surface.

4. In a high pressure fluid compressing machine, the combination withthemachine cylinder of a valve carrying body provided with an axialchannel and with a plurality of sloping channels surrounding the axialpassage and converging towards the cylinder, the surface of the bodyfacing the cylinder having a part spherical concave section into whichthe sloping channels open and a flat outer extension for said partspherical section, an annular suction valve having a surface matchingsaid part spherical surface and cooperating with the openings of thesloping channels facing the cylinder, a delivery valve cooperating withthe opening of the axial channel in the body at the end thereof facingaway from the cylinder, and means whereby the portion of the outer,periphery of the body extending between said openings of thesloping-channels and said opening of the axial channel is subjected tosuction pressure over a length equal to that of the axial channelsubjected to the pressure in the machine cylinder.

5'. Ida high pressure fluid compressing machine, the combination as setforth in claim 4, wherein the center of the radius of curvature of saidpart spherical concave section coincides wit-h the converging point ofthe axes of all sloping channels.

References Cited by the Examiner UNITED STATES PATENTS 1,614,851 1/1927Prestage 230-230 X 1,719,572 7/1927 Stoll 230-231 ROBERT M. WALKER,Primary Examinen

1. IN A HIGH PRESSURE FLUID COMPRESSING MACHINE, THE COMBINATION WITHTHE MACHINE CYLINDER OF A VALVE CARRYING BODY PROVIDED WITH AN AXIALCHANNEL AND WITH A PLURALITY OF SLOPING CHANNELS SURROUNDING THE AXIALPASSAGE AND CONVERGING TOWARDS THE CYLINDER, THE SURFACE OF THE BODYFACING THE CYLINDER HAVING A PART SPHERICAL CONCAVE SECTION INTO WHICHTHE SLOPING CHANNELS OPEN AND A FLAT OUTER EXTENSION FOR SAID PARTSPHERICAL SECTION, AN ANNULAR SUCTION VALVE HAVING A SURFACE MATCHINGSAID PART SPHERICAL SURFACE AND COOPERATING WITH THE OPENINGS OF THESLOPING CHANNELS FACING THE CYLINDER, A DELIVERY VALVE COOPERATING WITHTHE OPENING OF THE AXIAL CHANNEL IN THE BODY AT THE END THEREOF FACINGAWAY FROM THE CYLINDER, AND MEANS WHEREBY THE PORTION OF THE OUTERPERIPHERY OF THE BODY EXTENDING BETWEEN SAID OPENINGS